Goals set for the current year include: (1) defining the influence of various hormones and pharmacological agents on rates of neurite outgrowth from explants of the rat superior cervical ganglion, (2) examining the influence of low molecular weight constituents implicated in regulating growth in mammalian tissues, and (3) elucidating changes in lipid composition that occur in axotomized neural tissue. The retrograde response of nerve cell bodies to axonal injury is marked by profound changes in metabolism which are important determinants of axonal regeneration. Defining the nature of these metabolic changes and determining their relationship to axonal injury remains a major goal of neurobiology. During the course of this project we have developed a means of maintaining adult mammalian neural tissue in chemically defined media and have developed methods whereby rates of neurite growth may be altered experimentally and correlated with metabolic events within this tissue. Information obtained in studies using this system may be applied to defining substrates required for optimal growth of neuronal processes and may also lead to more rational means of promoting axonal growth with hormonal or pharmacological agents.